The present invention relates to a field emission cathode generally used for microsensors, high-speed switching devices and other various display devices and to a manufacturing method thereof and, more particularly, to a field emission cathode with high emission characteristics due to electron emission share and minimized tip abrasion, and to a manufacturing method thereof.
FIG. 1 is a vertical cross-sectional view of the conventional field emission cathode generally used in various areas as stated above.
First, to review the structure thereof, a cathode 2 having a needle-shaped field emission tip 4 is formed on a substrate 1 in a predetermined pattern, an oxide layer 3 is formed on the surface of the cathode around the tip 4, an insulation layer 5 is deposited thereon, and a pin hole 7 is finally formed. Also, a gate electrode 6 is deposited on the insulation layer 5.
To form such a structure, the processes proceed in the order as shown in FIGS. 3 to 8.
In other words, cathode layer 2 is deposited on the substrate 1 and the surface thereof is thermally oxidized to then form an oxide layer. The oxide layer is etched in a predetermined pattern to then form a mask as shown in FIG. 4. Thereafter, etching is performed as shown in FIG. 5 to shape an emitter tip on the cathode layer, roughly, and the surface is again thermally oxidized as shown in FIG.6. If the oxide layer is removed, a sharp needle-shaped emitter tip can be formed. Before the field emission tip is attained, first, an insulation layer 5 and a gate electrode 6 are deposited sequentially around the tip to surrounded the pin hole 7, as 10 shown in FIG. 7. Finally, the deposited layers on the tip are lifted off, the oxide layer is removed and then a needle-shaped tip is exposed, as shown in FIG.8.
In the conventional field emission cathode constituted as described above, a predetermined voltage potential is applied to the cathode 2 and gate electrode 6 and thereby electrons are extracted from the field emission tip 4 formed on the cathode by means of the electric field at a predetermined electrical potential.
However, in the conventional field emission cathode, since the field emission tip formed on the cathode is a single needle-like shape, which means that the surface width of electron emission is very narrow, few electrons are extracted. As shown in FIG. 2, in case the top of the field emitter tip 4 is damaged, the electron emission capability from the top of the field emission tip 4 is rapidly lowered.